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#101 2017-07-12 12:51:55

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: SLS and what asteriod will we go to

Well,  looking at their website,  it would appear that Rusty Schweikart has mostly retired.  Ed Lu is now running B612. 

The trouble is the same now as it was in 2009 at the Granada conference:  getting the funding to build and launch this thing.  I had lunch with Schweikart in Granada during that conference,  and according to him the problem then was a combination of "not invented here (NIH)" and "not one of our favored contractors (NFC)" at NASA. 

To the best of my knowledge,  NASA's Lindley Johnson still prefers to do this with all ground-based optical stuff,  and has limited resources.  He's the NASA leader who attends these asteroid defense conferences and runs those efforts within NASA.

Doesn't look like much has changed with regard to those NIH and NFC problems since the 2009 conference in Granada.  That's why B612 has been building the Sentinel thing with donations and crowdfunding.  That satellite is on the same order of magnitude cost as a modern commercial launch:  $10^8 each.  As I said earlier,  we could have one out there for under $1B.

We really do need more than one of these out there.  If B612 can get just one out there,  its results will be so superior to the ground based optical searches as to be utterly overwhelming.  Rub their noses in it,  so to speak.  That should break the NASA funding logjam.  Or affect USAF decisions if they get tasked with this mission.

Strategy-wise,  the imperative is first and foremost a really good NEO search down to 1-m size or smaller.  The smaller the better.  The second priority (not to be delayed, I might add!!) is comet watch,  because that is where the sudden surprise events will all come from,  once the 1-m NEO's are “known”.  The third item is both spacecraft development and composition and cohesiveness characterization,  which can be delayed.  Some.

Once a comet watch gets started,  and this NEO threat is characterized as a list of expected collisions over time (never certain beyond a few-to-several years because of the Yarkovski effect shifting orbits),  priority shifts to experimental development of (1) a standardized gravity tractor spacecraft,  and (2) a standardized weapons-delivery fly-by spacecraft,  for either impactors or nuclear charges.  This can be spread over time for a low cost in any given year.  It takes awhile to get this done and tested.

Right now the very best experts on gravity tractor techniques are in B612.  Several labs and entities have really good smarts about impactors.  Weapons outfits like Sandia and Livermore have the best smarts about nukes in space.  All that really means,  is that all these locations need to be funded working toward a well-coordinated plan.  They are not,  not right now. 

That composition and cohesiveness characterization gets done more like the planetary probe program,  as a series of missions of mostly-lower cost. These need to be a whole slew of small one-way asteroid and comet landings combined with impactors.  The objective is to characterize composition and cohesiveness to identify useful predictive trends.  It eventually gets supplemented with a couple of high-visibility manned visitations for in-situ experimentation. 

This supports the actual use of impactors and/or nukes for the short-warning comet defense problem.  That problem will always be with us precisely because it is a comet problem,  not so much an asteroid problem.  They simply cannot be seen until they get much closer and warm up a bit.  Speeds are high because of the very elongate orbits.

And as I also said earlier and elsewhere,  the ship that takes men to asteroids should be the same reusable vessel hardware that takes men to Mars.  You simply DO NOT do that with throwaway kick stages and abandoned modules. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#102 2017-07-12 18:44:48

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 26,753

Re: SLS and what asteriod will we go to

Like you noted back a page that the sensors are depth and field of view limited. To what they can detect in the position that they will orbit and face with regards to the sun.
I would purpose that the satelites should be design like a sonar sphere with regards to having multiple sensors per satelite to widen the FOV for each units orbit. Not only can you see the piece of rock but from sensor to sensor you can then determine with greater accuracy the speed to which it is traveling.

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#103 2017-07-12 20:38:58

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: SLS and what asteriod will we go to

Focus is pretty much at infinity.  The distance to the target divided by the focal length of the lens is effectively infinity.  Image plane distance can be fixed into the design.  If the lens diameter is small (effectively a large f-stop),  the depth of field is large.  That means a longer exposure to collect enough photons to get a signal larger than noise. 

Narrow field of view is no problem if you use a repeatable scan pattern.  This works just fine with non-imaging IR missile seekers.  The scan is what builds up the effective image. 

Staring-array imaging systems actually have a wide field of view,  eliminating the need to scan.  Modern ones are only limited by the total number of receptors,  each being one pixel of the image.  I don't know which approach Sentinel uses,  but both work very well,  and have worked well for many decades. 

This IR stuff works better if cooled,  usually to liquid nitrogen-class temperatures.  LN2 supply may well be the life-limiting factor for a Sentinel.  Unless someone figures out a way to go to one,  hook up,  and replenish the supply. 

There is no reason that capability could not be designed-in,  or retrofitted,  before launch.  Provides another good reason for a manned space flight program.  Those are shorter missions compared to Mars or the NEO's. 

GW

Last edited by GW Johnson (2017-07-12 20:51:25)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#104 2017-07-13 17:47:51

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,753

Re: SLS and what asteriod will we go to

Maybe soon we can get short duration missions with the use of Dragon V2, Starliner and with Dreamchaser but from what I have seen they all need a larger service module in order to do anything beyond linking up with the Station.

I can see active cooling of liquid nitrogen would be a good thing to do for the satelite design as it would be short lived.

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#105 2020-02-20 17:45:03

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,753

Re: SLS and what asteriod will we go to

The first thoughts for the SLS was to get a asteriod but that down sized to getting a boulder in orbit around the moon to no at all.

tahanson43206 wrote:

For Calliban re topic ...

It is time to bring your asteroid topic back into view.

The article at the link below describes work (apparently) done at MIT to focus on Apophis:

https://www.yahoo.com/news/mit-system-p … 27807.html

The cocoon idea has not yet migrated out of this little forum, but it could hitch a ride on an initiative from MIT.

The researcher quoted is at least thinking about sending probes to the asteroid.  That is a useful first step, and it should be encouraged, in my opinion.

However, the ** big ** interest is likely to come from the idea of harvesting the asteroid, instead of just deflecting it.

(th)

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#106 2022-09-14 10:32:38

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 4,782

Re: SLS and what asteriod will we go to

Musk might take over from SLS?


NASA’s latest moon mission is the dawn of a new space age
https://www.vox.com/recode/2022/8/27/23 … er-florida


Privatized Universe
https://newleftreview.org/sidecar/posts … d-universe

Ultra-hard 'lonsdaleite' diamonds found in Africa actually came from a dwarf planet, study finds
https://www.euronews.com/next/2022/09/1 … -machinery

Artemis 5 aka Artemis V is the fifth planned mission and third crewed landing of NASA's Artemis Program. The mission will launch four astronauts on a Space Launch System rocket and an Orion to the south pole of the Moon, Artemis V will also deliver two new elements to the Gateway Space Station.

https://spacenews.com/nasa-selects-falc … -elements/

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#107 2022-09-14 20:25:01

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,753

Re: SLS and what asteriod will we go to

Nasa has backed away from any such activity of the direct kind to bringing a rock to the moons orbit. Even the use of a starship is silly for this activity.

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#108 2022-09-23 17:47:47

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 4,782

Re: SLS and what asteriod will we go to

Just 3 days until DART smashes into an asteroid, and the Italian Space Agency's LICIACube is gearing up to take pictures of the big moment.
https://twitter.com/exploreplanets/stat … 5006794752

How to Watch NASA’s ‘Kinder, Gentler’ Megarocket Tanking Test
https://gizmodo.com/nasa-sls-tanking-te … 1849557886

NASA has chosen Falcon Heavy as the launch vehicle for its Psyche mission to a metallic asteroid, the Europa Clipper was initially targeted to be launched on an SLS rocket but due to extensive delays, in 2021 NASA awarded the launch contract to SpaceX.

Last edited by Mars_B4_Moon (2022-09-23 17:52:17)

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#109 2022-10-18 06:13:06

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 4,782

Re: SLS and what asteriod will we go to

Artemis 1 has a new launch date!

https://earthsky.org/space/artemis1-our-return-to-moon/

NASA says DART mission successfully smashed an asteroid aside in deep space

https://www.usatoday.com/story/news/nat … 468766002/

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